Environmental problems at root of economic crisis, argue researchers

President Reagan is struggling with an economy that seems both unresponsive and unpredictable. Is there something happening, some factor that is being overlooked by policymakers?

Lester Brown of Worldwatch Institute thinks there is. The world is on the edge of an economic crisis of environmental origin, he and his co-author, Pamela Shaw, argue in the environmental think tank's latest paper, ''Six Steps to a Sustainable Society.''

In the 1960s and '70s, they claim, there was a major change in our relationship to the basic commodities from which society is built. The amounts of wood, fish, beef, grain, and oil produced annually per person peaked and began to decline. The reason for the decline in the first four resources is environmental degradation, they say. For a number of years this trend was masked by cheap oil that allowed us to compensate for this in a number of ways. But, the current oil glut notwithstanding, the increasing price and gradually decreasing quantities of oil now force a discontinuation of these stopgap measures, Mr. Brown and co-author Shaw argue.

Unfortunately, Brown says, policymakers like Ronald Reagan are trying to apply obsolete economic nostrums to the symptoms of this situation. Today's values and priorities don't yet mesh with ''the unfolding environmental and resource realities. As circumstances change, values must change accordingly. When they do not, societies do not long endure,'' the Worldwatch researchers warn.

They say today's challenges can be solved only by methods outside traditional economic policy. They propose six steps that they believe can put the world on an even keel economically, socially, and environmentally:

* Increase the effort to control population with the goal of stabilizing global population at 6 billion by the year 2020.

* Give soil conservation and agricultural land preservation a much higher priority despite the short-term increases in the cost of food that will result.

* Initiate an ambitious program to ''reforest the Earth'' to counteract the destruction of forest lands which are shrinking by an area the size of Hungary each year.

* Implement the policies necessary to move beyond a throwaway society to an economy based on recycling.

* Continue and accelerate the progress already being made toward using energy more efficiently.

* Push faster to develop new renewable sources of energy to replace oil.

Of these steps, Brown considers population control the most crucial. Developing and deploying more energy-efficient devices and renewable energy sources, on the other hand, will be the most expensive.

These problems cannot be left to the ''free market,'' Brown argues, because ''the market has no alarm that sounds when the carrying capacity of a biological system is exceeded.''